1. Field of the invention
This invention relates to a circulation apparatus and, more particularly, relates to a circulation apparatus which is capable of compensating for or supplementing the function of a heart to circulate the blood.
2. Description of the prior art
In the area of artificial organs, especially artificial hearts, various proposals have been made or put into practical use in recent years.
As a circulation apparatus which supplements the blood circulating function of a heart with deteriorated blood circulating abilities, for example, an apparatus which utilizes an air compressor coupled to a diaphragm pump, pusher plate pump or the like has become commercially available.
However, in a conventional circulation apparatus which uses a diaphragm pump as shown in FIG. 5, a compressor must be installed outside the body to supply air (indicated by arrow A in the drawing) in the casing a or exhaust the air (indicated by arrow A' in the drawing) from the casing a in order to drive a diaphragm b (directions of the movements are indicated by B and B' in the drawing), and the pump and the compressor must be connected. Installation of such a circulation apparatus on a patient's body causes substantial restriction on the patient's body movement.
On the other hand, in another conventional apparatus which comprises a pusher plate c as shown in FIG. 6, a compliance chamber is required to accommodate the changes of the inner volume of the casing e accompanying the vertical movement of the piston d (directions of the movements are indicated by D and D' in the drawing) which drives the pusher plate c (directions of the movements are indicated by C and C' in the drawing). If a circulation apparatus of such a constitution as described above is to be planted in a human body, a space must be made in the body to accommodate the pump h and the compliance chamber i, each having a bypass passage g made of an artificial blood vessel, with the bypass passage g sutured to the heart j, for example, as shown in FIG. 7. This results in a problem of the pump h and the compliance chamber i exerting pressure on other organs.
In both FIG. 5 and FIG. 6, the reference numeral f denotes a valve.
These conventional circulation apparatuses have other problems such that the bypass blood passages required in every case makes the surgery of connecting the apparatus to the heart extremely difficult and that complexity of the apparatus construction results in poor reliability of the apparatus and that large area of contact with blood leads to great probability of causing thrombus.